The Low Smoke Myth
Many polymeric cable manufacturers claim the polymers they use for insulation and jackets are low smoke.
They often justify this by claiming compliance to tests like BS EN 61034.
These smoke obscuration tests are dependent on a specific sample weight of cable burned in a specific room / air volume. These results are not predictive end use simulations.
Smoke generation can be greater on high heating before flame and smoke volume is directly related to the amount of material burnt.
Images from Singapore MRT 2013 - Newton Underground Station. Cable overloaded and caught fire.
So how can a BS-EN 61034 low smoke cable give off so much smoke?
PVC gives off more smoke in flame but PE / XLPE (polyethylene) gives off more smoke on heating without flame.
|
Material |
Thickness (mm) |
Maximum Specific Optical Density (DM) Non Flaming |
Flaming |
|
Plastics; |
|
|
|
|
UPVC |
3 |
400 |
580 |
|
Polyethylene |
3 |
590 |
83 |
|
FR Polyethylene |
3 |
790 |
780 |
|
Polypropylene |
3 |
550 |
162 |
|
FR Polypropylene |
3 |
820 |
600 |
|
Polystyrene |
3 |
476 |
960 |
|
PMMA |
3 |
63 |
117 |
|
Plasticised PVC |
0.75 |
430 |
650 |
Plasticized UPVC is used to make a general electric cable. In flaming and none flaming mode both feature high smoke outputs, indeed very bad as a fireproof cable…
FP200 & FP600 use polyethylene – In a direct flame yes it shows as low smoke generation factor…. But under overload, short circuit or internal heat for any reason… 590DM is a lot of smoke!
It doesn’t take an actual fire to cause an emergency evacuation, smoke with no fire is more common and extremely costly!
Please contact us with your requirements.
